In brief: Iron deficiency is one of the world's most common nutritional problems. When severe, it causes anemia—too few healthy red blood cells to carry oxygen. Symptoms include fatigue, breathlessness, and pale skin. Blood tests (CBC and ferritin) confirm diagnosis. Treatment combines iron-rich foods, supplements when needed, and finding the underlying cause—such as heavy periods or hidden bleeding.
Common symptoms
- Fatigue, weakness, poor concentration
- Shortness of breath on exertion
- Pale skin, brittle nails, hair thinning
- Restless legs, cravings for ice or starch (pica) in some people
- Heavy periods are a frequent cause in women of reproductive age
Similar fatigue occurs with B12 deficiency and thyroid disorders—blood tests help distinguish causes.
Key blood tests
Clinicians typically check full blood count (CBC), ferritin (iron stores), and sometimes iron saturation and transferrin. Ferritin can be falsely normal during inflammation—your doctor interprets results in context. See our blood test results guide for more on lab panels.
Important causes to investigate
- Low dietary iron, pregnancy, rapid growth in children
- Heavy menstrual bleeding
- Digestive conditions (coeliac disease, inflammatory bowel disease)
- Hidden gastrointestinal bleeding—especially in adults with anemia without an obvious cause
Best foods to improve iron levels
- Haem iron (better absorbed): lean red meat, poultry, fish
- Non-haem iron: spinach, lentils, beans, fortified cereals, tofu
- Boost absorption: pair plant iron with vitamin C (citrus, peppers, tomatoes)
- Limit with meals: tea, coffee, and calcium supplements close to iron-rich meals
Diet alone may not correct significant deficiency—supplements or IV iron are often needed under medical supervision.
Treatment
Oral iron is first-line for many people; intravenous iron may be used when oral iron fails or is not tolerated. Treat the underlying cause—not only the supplement. Take iron as directed; excess iron is harmful.
Frequently asked questions
What ferritin level indicates iron deficiency?
Thresholds vary by lab and context, but ferritin below roughly 30 ng/mL often suggests low stores in adults without inflammation. Your clinician interprets alongside CBC and symptoms.
Can I take iron without a blood test?
Not recommended. Iron overload can damage organs. Test first, then supplement with a planned recheck.
Why do I feel worse after starting iron tablets?
Constipation, nausea, and dark stools are common. Taking with food, switching formulation, or adjusting dose with your doctor may help.
When is hidden gut bleeding suspected?
Adults—especially men and post-menopausal women—with anemia without clear cause often need endoscopy to rule out bleeding lesions.
Questions to ask your doctor
- Is my ferritin low enough to explain my symptoms?
- Do I need tests for bleeding or malabsorption?
- Which iron supplement and dose do you recommend?
- When should we recheck my blood count?
- Could my heavy periods or diet be the main driver?
Trusted references
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If you have symptoms or risk factors discussed here, book a consultation with a verified doctor, visit a hospital, or arrange lab tests near you. Early assessment matters.
Educational content from DoctorBookly Editorial. Not personal medical advice. Always consult a licensed clinician for diagnosis, treatment, and emergencies. Call your local emergency number if you think you are having a medical emergency.
